US4879992A - Rigid electronic endoscope - Google Patents

Abstract

This rigid electronic endoscope has an endoscope having an elongate insertable part connected to the front part of an operating part which is also a holding part on the base side and formed of a solid state imaging device which can output an electric signal by electrically converting an object image in this insertable part and a conductive shielding member sheathing this insertable part. The electric signal obtained by this endoscope is input into a signal processing circuit. The ground terminal of this signal processing circuit is electrically connected to the above mentioned shielding member and is isolated from a ground terminal on the external current source side.

Description

FIELD OF THE INVENTION

This invention relates to a rigid electronic endoscope forming a shielding means.

BACKGROUND OF THE INVENTION

Recently, there has come to be extensively used an endoscope whereby an affected part or the like within a body cavity can be observed or diagnosed by inserting an elongate insertable part into the body cavity or a curing treatment can be made by using treating tools as required.

Also, there is recently practiced an electronic endoscope (mentioned also as an electronic scope) whereby an image is formed on an imaging surface of a solid state imaging device by objective lenses without using an image guide formed of a fiber bundle and a video signal photoelectrically converted by this solid state imaging device is transmitted to a signal processing means and is color-displayed by a monitor.

Now, in the above mentioned electronic endoscope, when such electric device as a high frequency treating tool is used, a high frequency noise will be output, will be therefore likely to be mixed in an output video signal of the solid state imaging device, will appear on the displaying picture surface and will remarkably reduce the picture quality of the endoscope picture imaged by the solid state imaging device and, in fact, an observation or diagnosis will be no longer able to be made.

In the publication of a U.S. Pat. No. 4,607,621, for the protection from such high frequency noise, there is disclosed a technique wherein an imaging device and video and signal transmitting electric wires are contained in a conductive shield which is electrically connected to a chassis of a video processor and further this chassis is connected to an RF earthing point of a high frequency current source apparatus.

Now, in this technique, as the chasis and shield are connected with each other, a leaking electric current will be likely to flow out of the shield to cause a very dangerous state.

OBJECT AND SUMMARY OF THE INVENTION

An object of the present invention is to provide a rigid electronic endoscope having a sufficient shielding function against high frequency noises and capable of obtaining an endoscope picture of a required picture quality.

The rigid electronic endoscope of the present invention is provided with an endoscope having a solid state imaging device as an imaging means and a controlling apparatus containing a signal processing circuit for the electric signal output from this endoscope. A conductive shielding member to externally shield this endoscope is connected to the ground terminal of the above mentioned signal processing circuit to form a shielding means.

The other features and advantages of the invention will become apparent enough with the following explanation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 relates to the first embodiment of the present invention and a formation view of a rigid electronic endoscope.

FIG. 2 relates to the second embodiment of the present invention and is a formation view of a rigid electronic endoscope.

FIG. 3 relates to the third embodiment of the present invention and is a formation view of a rigid electronic endoscope.

Fog. 4 relates to the fourth embodiment of the present invention and is a formation view of a rigid electronic endoscope.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention shall be concretely explained in the following with reference to the drawings.

A rigid electronic endoscope apparatus 1 of the first embodiment is formed of a rigidelectronic endoscope body 2 and anendoscope controlling apparatus 4 connected to this (rigid electronic)endoscope body 2 through aconnecting tube 3.

The above mentionedendoscope body 2 is covered with ametallic sheath tube 5 made of a copper alloy or Ni-Cr plated stainless steel and is connected with aflexible connecting tube 3 extended out of the side part of the rear end side of thissheath tube 5.

The above mentioned connectingtube 3 has ashielding net tube 3a or the like made by knitting metal wires or the like to be net-like. This shieldingnet tube 3a is electrically connected to thesheath tube 5 but is electrically isolated from asheathing metal part 6 of the controllingapparatus 4.

The above mentionedsheath tube 5 is formed to be like a thin circular tube through which alight guide 7 formed of a fiber bundle is inserted. Thislight guide 7 is further inserted through the connectingtube 3 and is fed with a white illuminating light from alight source lamp 8 of the controllingapparatus 4. The illuminating light radiated onto the entrance end surface on the base side of thislight guide 7 is transmitted by thelight guide 7 and is radiated toward an object to be imaged from the tip surface of this light guide. The image of the illuminated object is formed by anobjective lens system 9 arranged adjacently to the tip part of thelight guide 7 on a CCD (charge coupled device) 11 having the imaging surface arranged in the focal plane of thisobjective lens system 9. This CCD 11 photoelectrically converts the optical image formed on the imaging surface and outputs a photoelectrically converted video (picture) signal by the application of a CCD driving signal output from a driving circuit not illustrated, for example, within the controlling apparatus. By the way, acolor mosaic filter 12 in which red, green and blue color transmitting filters are arranged in the form of a mosaic by the pixel unit or the like is arranged on the imaging surface of the CCD 11. Therefore, the picture signal output from the CCD 11 becomes a color picture signal. This picture signal is transmitted through thesignal cable 13 and is input into avideo process circuit 14 within the controllingapparatus 4. By thisvideo process circuit 14, the input picture signal is treated to be separated in colors, is converted to an NTSC compound video signal or RGB3-primary color signals, is output in an observingmonitor 16 through avideo cable 15 and is output also in a flat plate-like display 18 fitted near the base side end of theendoscope body 2 through avideo cable 17 inserted through theendoscope body 2 to color-display the object image by themonitor 16 and (flat plate-like)display 18.

The above mentionedvideo process circuit 14 is to be fed with an electric power from a commercial current source as electrically isolated through anisolation circuit 19.

Now, the ground (GND)terminal 14a of the above mentionedvideo process circuit 14 is connected with one place, for example, on the rear end side of thesheath tube 5 through anearthing line 21 and the potential of thesheath tube 5 is held on the GND level of thevideo process circuit 14.

By the way, as the connectingtube 3 is electrically connected with thesheath tube 5 by theshielding net tube 3a, thisshielding net tube 3a is held on the same level as of the GND of thevideo process circuit 14.

On the other hand, thesheathing metal part 6 is connected to the GND of a commercial current source, that is, to the earth by anearthing line 22. TheGND terminal 14a of thevideo process circuit 14 is in a floating state from the GND of this commercial current source.

By the way, thesheath tube 5 as fitted in ajacket tube 23 can be inserted into a body cavity or the like. Thisjacket tube 23 is made of a stainless steel or Ni-Cr plated copper alloy the same as in thesheath tube 5 and is in mechanical and electrical contact with thesheath tube 5.

In this first embodiment, it is a feature that themetallic sheath tube 5 forming the sheathing member of theendoscope body 2 is connected with theGND terminal 14a of thevideo process circuit 14 into which the video signal of the CCD 11 shielded with thesheath tube 5 and thisGND terminal 14a is in a floating state with the GND terminal on the external current source side to form a shielding means.

By the way, the forceps channel not illustrated is made of a metal or is covered with a metal so that, in case a high frequency treating tool is used, the radiation on the periphery may be reduced, is electrically connected with thesheath tube 5 and is held at the same potential as of thissheath tube 5.

According to the thus formed first embodiment, for example, in case a high frequency treating tool is used by an electric power fed from as commercial current source, the high frequency waves will be prevented by thesheath tube 5 of the like from being mixed as noises into theoutput signal cable 13 of CCD 11. Also, the high frequency output circuit side outputting the electric power for the high frequency treating tool and thevideo process circuit 14 side are isolated from each other by theisolation circuit 19, the GND of thevideo process circuit 14 is in a floating state against the GND (substantially equal to the earthing of the commercial current source) of the high frequency output circuit and therefore, even if a high frequency noise mixes in thesignal cable 13, this high frequency noise will be substantially of the same potential as of the GND of the video process circuit 14 (as different from the case that the GND of thevideo process circuit 14 must be isolated from the GND of the high frequency output circuit) and will not substantially influence the signal.

Therefore, the deterioration of S/N can be made small and the reduction of the picture quality can be made small enough.

FIG. 2 shows the second embodiment, of the present invention. In a rigidelectronic endoscope apparatus 31 of this second embodiment, thejacket tube 23 in the electronic endoscope apparatus 1 shown in FIG. 1 is made ajacket tube 32 of a structure of three layers.

That is to say, thejacket tube 32 consists of three layers of aninner layer 33,middle layer 34 andouter layer 35. Each of theinner layer 33 andouter layer 35 is formed of an insulating member. Themiddle layer 34 is formed of such conductive member as of a metal and is earthed through anearthing line 36.

In this second embodiment, as theinner layer 33 is formed of an insulating member, thesheath tube 5 of theendoscope body 2 will not be of the earthing potential and thisbody 2 will be held in a floating state.

Also, as theouter layer 35 is formed of an insulating member, in the case of the use within a body cavity, the patient himself will be able not to be of the earthing potential.

The others are of the same formation as of the above mentioned first embodiment. The same reference numerals are attached respectively to the same members.

In this second embodiment, as themiddle layer 34 of thejacket tube 32 is earthed, thismiddle layer 34 will further have a shielding function against external noises and noises will be able to be well prevented from mixing into the CCD output signal.

FIG. 3 shows the third embodiment of the present invention.

In a rigidelectronic endoscope apparatus 41 of this third embodiment, there is used adummy cable 42 to be a twisted pair twisted together with thesignal cable 13 transmitting the picture signal of the CCD. Thisdummy cable 42 is connected at the end on the CCD 11 side to aGND terminal 43 of the CCD 11 through a resistance R and is led at the end on the base side to the rear step side through adifferential amplifier 45 within thevideo process circuit 44. By the way, the above mentionedGND terminal 43 of the CCD 11 is of the same potential as of the GND terminal of thevideo process circuit 44.

The above mentioned resistance R is set to be equal to the output impedance of the CCD 11. Thesignal cable 13 anddummy cable 42 are made a twisted pair so that, in case high frequency noises mix in the reverse phase, they may be canceled with each other. On the other hand, by passing the same phase component through thedifferential amplifier 45, the high frequency noises are canceled.

By the way, in this embodiment, thejacket tube 46 together with the guide tube part through which theendoscope body 2 is inserted forms a treatingtool channel 47 through which the treating tool can be passed.

The other are of the same formation as of the above mentioned first embodiment. The same reference numerals are attached respectively to the same components.

According to this third embodiment, by obtaining the differential output of bothcables 13 and 42, the external noises can be more effectively removed, the reduction of S/N can be prevented and the deterioration of the picture quality can be prevented.

By the way, in the above described respective embodiments, the rigid endoscope has been explained. However, the present invention is not limited to it but can be applied the same to a flexible electronic endoscope using a solid state imaging device for the imaging means. In such case, as a conductive sheath member corresponding to themetallic sheath tube 5 in FIG. 1 and having a noise shielding function, such tip forming member as a net tube (blade) or spiral tube (flex) may be used as made electrically conductive. Also, the forceps channel may be formed of such conductive member as a net tube. The above described embodiments may be combined.

FIG. 4 shows the fourth embodiment of the present invention.

A rigidelectronic endoscope 51 of this embodiment is the rigid electronic endoscope 1 of the first embodiment in which the imaging system is made to be of a frame sequential type.

Asheath tube 5 is formed to be like a small diameter cylindrical tube. Alight guide 7 formed of a fiber bundle is inserted through thissheath tube 5, is further inserted through a connectingtube 3 and is connected to acontrol apparatus 4. An illuminating light emitted from alight source lamp 8 and having passed through a plurality of color transmitting filters provided in arotary filter 52 will enter the entrance end surface of thislight guide 7. These plurality of color transmitting filters can respectively transmit color lights, for example, of red, green and blue and can emit red, green and blue color lights when therotary filter 52 is rotated and driven by amotor 53. An object illuminated by these illuminating lights will be made to form an image on the imaging surface of a CCD 11 by anobjective lens system 9. This optical image will be photoelectrically converted by the CCD 11. This photoelectrically converted video signal will be output by the application of a CCD driving signal output from a driving circuit not illustrated, for example, within thecontrol apparatus 4. This video signal will be processed by aprocess circuit 14 within thecontrol apparatus 4.

The others are of the same formation as of the first embodiment. The same reference numerals are attached to the same members.

In this embodiment, as the imaging system is made to be of a frame sequential type, the imaging surface of the CCD 11 can be made small and thesheath tube 5 can be made smaller in the diameter than in the above mentioned respective embodiments.

As described above, according to the present invention, the signal processing means processing the output video signal of the solid state imaging device is made in a floating state from the earthing of the external power feeding means by the isolation means, the ground of this signal processing means is conducted with the sheath member of the endoscope body and therefore noises can be prevented from mixing into the video signal to reduce S/N.

Claims (4)

What is claimed is:

1. A rigid electronic endoscope, comprising:

an endoscope having an elongated insertable portion which is connected to a front portion of an operating part, a holding part on an end portion of said endoscope, a solid state imaging means for outputting an electrical signal by electrically converting an object image within said insertable portion, and a sheath means of said insertable portion for forming a conductive shielding means;

a signal processing means connected to said imaging means, for processing said electrical signal obtained by said endoscope, said signal processing means having a first ground terminal means; and

an external current source means connected to said signal processing means, said external current source means having a second ground terminal means, said shielding means being connected to said second ground terminal means, wherein said first ground terminal means and said second ground terminal means are isolated from each other for preventing high frequency waves on said sheath means from effecting said electrical signal output of said endoscope.

2. A rigid electronic endoscope according to claim 1 wherein said insertable portion is inserted in a jacket tube.

3. A rigid electronic endoscope according to claim 2 wherein said jacket tube is isolated from said shielding means.

4. A rigid electronic endoscope according to claim 1 wherein a dummy cable for removing noises is electrically connected to said solid state imaging means and signal processing means.

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